首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   78814篇
  免费   8025篇
  国内免费   4997篇
电工技术   6606篇
技术理论   2篇
综合类   6585篇
化学工业   10960篇
金属工艺   5049篇
机械仪表   5475篇
建筑科学   5919篇
矿业工程   2398篇
能源动力   2486篇
轻工业   5333篇
水利工程   2041篇
石油天然气   3988篇
武器工业   1107篇
无线电   9319篇
一般工业技术   8089篇
冶金工业   3589篇
原子能技术   1052篇
自动化技术   11838篇
  2024年   304篇
  2023年   955篇
  2022年   2049篇
  2021年   2984篇
  2020年   2259篇
  2019年   1770篇
  2018年   1954篇
  2017年   2382篇
  2016年   2274篇
  2015年   3228篇
  2014年   4188篇
  2013年   4794篇
  2012年   6101篇
  2011年   6398篇
  2010年   6063篇
  2009年   5791篇
  2008年   5746篇
  2007年   5410篇
  2006年   4965篇
  2005年   4107篇
  2004年   3148篇
  2003年   2881篇
  2002年   3039篇
  2001年   2665篇
  2000年   1687篇
  1999年   1252篇
  1998年   689篇
  1997年   621篇
  1996年   513篇
  1995年   412篇
  1994年   303篇
  1993年   206篇
  1992年   143篇
  1991年   118篇
  1990年   103篇
  1989年   90篇
  1988年   64篇
  1987年   40篇
  1986年   34篇
  1985年   10篇
  1984年   15篇
  1983年   17篇
  1982年   12篇
  1981年   15篇
  1980年   12篇
  1979年   5篇
  1978年   4篇
  1975年   3篇
  1959年   5篇
  1951年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
With the rapid development of network technologies and deteriorating of network environment, traditional single-net security system cannot satisfy the security requirement. The excellent security performance of biological systems impels the bio-inspired network security theory to be a hot research area currently. Based on Bio-inspired Multidimensional Network Security Model we have put forward, we have advanced Bio-inspired Multi-Net Security system by implementing the functional distribution of different subnets of different transient states in Multi-Net Paralleling structure. Firstly, parameter estimation and modified algorithms of Hidden Markov Model are introduced to construct the mathematical mode of B-MNS; secondly, the integrated performance of our modified B-MNS has been tested and its simulation has been carried out. So the feasibility, validity and high efficiency of our model have been demonstrated theoretically, and practically.  相似文献   
62.
In this paper, a single-iteration strategy is proposed for the design of a multi-loop PI controller to achieve the desired gain and phase margins for two-input and two-output (TITO) processes. To handle loop interactions, a TITO system is converted into two equivalent single loops with uncertainties drawn from interactions. The maximum uncertainty is estimated for the initial controller design in one loop and single-input and single-output (SISO) controller design is applied. This controller is substituted to other equivalent loop for design, and finally, the first loop controller is refined on knowledge of other loop controller. For SISO controller tuning, a new method is presented to determine the achievable gain and phase margins as well as the relevant controller parameters. Examples are given for illustration and comparison.  相似文献   
63.
Contaminant intrusion in a water distribution network is a complex but a commonly observed phenomenon, which depends on three elements – a pathway, a driving force and a contamination source. However, the data on these elements are generally incomplete, non-specific and uncertain. In an earlier work, Sadiq, Kleiner, and Rajani (2006) have successfully applied traditional Dempster–Shafer theory (DST) to estimate the “risk” of contaminant intrusion in a water distribution network based on limited uncertain information. However, the method used for generating basic probability assignment (BPA) was not very flexible, and did not handle and process uncertain information effectively. In this paper, a more pragmatic method is proposed that utilizes “soft” computing flexibility to generate BPAs from uncertain information. This paper compares these two methods through numerical examples, and demonstrates the efficiency and effectiveness of modified method.  相似文献   
64.
65.
For motion compensated de-interlace, the accuracy and reliability of the motion vectors have a significant impact on the performance of the motion compensated interpolation. In order to improve the robustness of motion vector, a novel motion estimation algorithm with center-biased diamond search and its parallel VLSI architecture are proposed in this paper. Experiments show that it works better than conventional motion estimation algorithms in terms of motion compensation error and robustness, and its architecture overcomes the irregular data flow and achieves high efficiency. It also efficiently reuses data and reduces the control overhead. So, it is highly suitable for HDTV applications.  相似文献   
66.
In this paper, we propose a general optimization-based model for classification. Then we show that some well-known optimization-based methods for classification, which were developed by Shi et al. [Data mining in credit card portfolio management: a multiple criteria decision making approac. In: Koksalan M, Zionts S, editors. Multiple criteria decision making in the new millennium. Berlin: Springer; 2001. p. 427–36] and Freed and Glover [A linear programming approach to the discriminant problem. Decision Sciences 1981; 12: 68–79; Simple but powerful goal programming models for discriminant problems. European Journal of Operational Research 1981; 7: 44–60], are special cases of our model. Moreover, three new models, MCQP (multi-criteria indefinite quadratic programming), MCCQP (multi-criteria concave quadratic programming) and MCVQP (multi-criteria convex programming), are developed based on the general model. We also propose algorithms for MCQP and MCCQP, respectively. Then we apply these models to three real-life problems: credit card accounts, VIP mail-box and social endowment insurance classification. Extensive experiments are done to compare the efficiency of these methods.  相似文献   
67.
68.
针对实验室仪器信息统计中的准确性、完整性欠缺及低效率等问题,设计了一种全新的实验室仪器信息采集系统,以低功耗网络微处理器W7100A为系统的主控制器,通过SHT11温湿度传感模块和ZLG500AT射频IC模块直接采集仪器的环境参数等信息,通过用户与上位机客户端软件交互的方式采集仪器的工作内容等信息,相较于传统的手工记录方式,信息采集的及时性、完整性、可靠性方面都有了极大的提高.  相似文献   
69.
Lu  Gui-Fu  Zou  Jian  Wang  Yong  Wang  Zhongqun 《Multimedia Tools and Applications》2017,76(14):15801-15816
Multimedia Tools and Applications - Null space based linear discriminant analysis (NSLDA) is a well-known feature extraction method, which can make use of the most discriminant information in the...  相似文献   
70.
介绍在AutoCAD 2 0 0 0上 ,如何运用ObjectARX开发集流体动密封压力接头选型、设计绘图与客户信息查询于一体的CAD软件系统。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号